Path Computation Elements (PCEs) may be used for computation of paths in numerous advantageous situations, such as inter-domain (Autonomous Systems/Area or AS/area) path computation. For example, in conjunction with Multi-Protocol Label Switching Traffic Engineering (MPLS TE), PCEs may be used to compute shortest constrained paths across domains (e.g., for tunnels), diverse paths, etc. One concern with such an architecture is that the PCE becomes a critical component, and its failure and performance have a direct impact on the rerouting times of tunnels that use the PCE for their path computation. This is particularly critical because inter-domain tunnels (e.g., TE-LSPs or Label Switched Paths) are typically used to carry highly critical traffic (e.g., voice traffic, special Virtual Private Network or “VPN” traffic, all traffic, etc.). Accordingly, it is increasingly important to consider PCE failure and response time when designing and implementing a computer network.
Generally, PCE functions are hosted on a border router (BR) between domains, and there are typically at least two BRs, so there is no single point of failure. Mechanisms have been designed so as to quickly redirect the traffic toward/onto other BRs/PCEs in the event of a failure of another BR/PCE. One problem associated with this, however, is that the response time of the BR/PCE receiving the redirected traffic may be directly affected because the receiving PCE may now receive path computation requests from all Path Computation Clients (PCCs) in the domains originally utilizing the failed PCE (e.g., also requests from PCCs of other/remote domains with tunnels terminating/traversing in the failed PCE's domain). Often, too, path computation requests occur in bursts, such as after a network element (node/link) failure, which can affect hundreds or thousands of tunnels.